rebase: update kubernetes to latest

updating the kubernetes release to the
latest in main go.mod

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

vendor/github.com/google/cel-go/common/ast/BUILD.bazel

@@ -1,12 +1,7 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 package(
-    default_visibility = [
-        "//cel:__subpackages__",
-        "//checker:__subpackages__",
-        "//common:__subpackages__",
-        "//interpreter:__subpackages__",
-    ],
+    default_visibility = ["//visibility:public"],
     licenses = ["notice"],  # Apache 2.0
 )
 
@@ -14,10 +9,14 @@ go_library(
     name = "go_default_library",
     srcs = [
         "ast.go",
+        "conversion.go",
         "expr.go",
+        "factory.go",
+        "navigable.go",
     ],
     importpath = "github.com/google/cel-go/common/ast",
     deps = [    
+        "//common:go_default_library",
         "//common/types:go_default_library",
         "//common/types/ref:go_default_library",
         "@org_golang_google_genproto_googleapis_api//expr/v1alpha1:go_default_library",
@@ -29,7 +28,9 @@ go_test(
     name = "go_default_test",
     srcs = [
         "ast_test.go",
+        "conversion_test.go",
         "expr_test.go",
+        "navigable_test.go",
     ],
     embed = [
         ":go_default_library",
@@ -48,5 +49,6 @@ go_test(
         "//test/proto3pb:go_default_library",
         "@org_golang_google_genproto_googleapis_api//expr/v1alpha1:go_default_library",
         "@org_golang_google_protobuf//proto:go_default_library",
+        "@org_golang_google_protobuf//encoding/prototext:go_default_library",
     ],
-)
+)

vendor/github.com/google/cel-go/common/ast/ast.go

@@ -16,74 +16,361 @@
 package ast
 
 import (
-	"fmt"
-
+	"github.com/google/cel-go/common"
 	"github.com/google/cel-go/common/types"
 	"github.com/google/cel-go/common/types/ref"
-
-	structpb "google.golang.org/protobuf/types/known/structpb"
-
-	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
 )
 
-// CheckedAST contains a protobuf expression and source info along with CEL-native type and reference information.
-type CheckedAST struct {
-	Expr         *exprpb.Expr
-	SourceInfo   *exprpb.SourceInfo
-	TypeMap      map[int64]*types.Type
-	ReferenceMap map[int64]*ReferenceInfo
+// AST contains a protobuf expression and source info along with CEL-native type and reference information.
+type AST struct {
+	expr       Expr
+	sourceInfo *SourceInfo
+	typeMap    map[int64]*types.Type
+	refMap     map[int64]*ReferenceInfo
 }
 
-// CheckedASTToCheckedExpr converts a CheckedAST to a CheckedExpr protobouf.
-func CheckedASTToCheckedExpr(ast *CheckedAST) (*exprpb.CheckedExpr, error) {
-	refMap := make(map[int64]*exprpb.Reference, len(ast.ReferenceMap))
-	for id, ref := range ast.ReferenceMap {
-		r, err := ReferenceInfoToReferenceExpr(ref)
-		if err != nil {
-			return nil, err
-		}
-		refMap[id] = r
+// Expr returns the root ast.Expr value in the AST.
+func (a *AST) Expr() Expr {
+	if a == nil {
+		return nilExpr
 	}
-	typeMap := make(map[int64]*exprpb.Type, len(ast.TypeMap))
-	for id, typ := range ast.TypeMap {
-		t, err := types.TypeToExprType(typ)
-		if err != nil {
-			return nil, err
-		}
-		typeMap[id] = t
-	}
-	return &exprpb.CheckedExpr{
-		Expr:         ast.Expr,
-		SourceInfo:   ast.SourceInfo,
-		ReferenceMap: refMap,
-		TypeMap:      typeMap,
-	}, nil
+	return a.expr
 }
 
-// CheckedExprToCheckedAST converts a CheckedExpr protobuf to a CheckedAST instance.
-func CheckedExprToCheckedAST(checked *exprpb.CheckedExpr) (*CheckedAST, error) {
-	refMap := make(map[int64]*ReferenceInfo, len(checked.GetReferenceMap()))
-	for id, ref := range checked.GetReferenceMap() {
-		r, err := ReferenceExprToReferenceInfo(ref)
-		if err != nil {
-			return nil, err
-		}
-		refMap[id] = r
+// SourceInfo returns the source metadata associated with the parse / type-check passes.
+func (a *AST) SourceInfo() *SourceInfo {
+	if a == nil {
+		return nil
 	}
-	typeMap := make(map[int64]*types.Type, len(checked.GetTypeMap()))
-	for id, typ := range checked.GetTypeMap() {
-		t, err := types.ExprTypeToType(typ)
-		if err != nil {
-			return nil, err
-		}
-		typeMap[id] = t
+	return a.sourceInfo
+}
+
+// GetType returns the type for the expression at the given id, if one exists, else types.DynType.
+func (a *AST) GetType(id int64) *types.Type {
+	if t, found := a.TypeMap()[id]; found {
+		return t
 	}
-	return &CheckedAST{
-		Expr:         checked.GetExpr(),
-		SourceInfo:   checked.GetSourceInfo(),
-		ReferenceMap: refMap,
-		TypeMap:      typeMap,
-	}, nil
+	return types.DynType
+}
+
+// SetType sets the type of the expression node at the given id.
+func (a *AST) SetType(id int64, t *types.Type) {
+	if a == nil {
+		return
+	}
+	a.typeMap[id] = t
+}
+
+// TypeMap returns the map of expression ids to type-checked types.
+//
+// If the AST is not type-checked, the map will be empty.
+func (a *AST) TypeMap() map[int64]*types.Type {
+	if a == nil {
+		return map[int64]*types.Type{}
+	}
+	return a.typeMap
+}
+
+// GetOverloadIDs returns the set of overload function names for a given expression id.
+//
+// If the expression id is not a function call, or the AST is not type-checked, the result will be empty.
+func (a *AST) GetOverloadIDs(id int64) []string {
+	if ref, found := a.ReferenceMap()[id]; found {
+		return ref.OverloadIDs
+	}
+	return []string{}
+}
+
+// ReferenceMap returns the map of expression id to identifier, constant, and function references.
+func (a *AST) ReferenceMap() map[int64]*ReferenceInfo {
+	if a == nil {
+		return map[int64]*ReferenceInfo{}
+	}
+	return a.refMap
+}
+
+// SetReference adds a reference to the checked AST type map.
+func (a *AST) SetReference(id int64, r *ReferenceInfo) {
+	if a == nil {
+		return
+	}
+	a.refMap[id] = r
+}
+
+// IsChecked returns whether the AST is type-checked.
+func (a *AST) IsChecked() bool {
+	return a != nil && len(a.TypeMap()) > 0
+}
+
+// NewAST creates a base AST instance with an ast.Expr and ast.SourceInfo value.
+func NewAST(e Expr, sourceInfo *SourceInfo) *AST {
+	if e == nil {
+		e = nilExpr
+	}
+	return &AST{
+		expr:       e,
+		sourceInfo: sourceInfo,
+		typeMap:    make(map[int64]*types.Type),
+		refMap:     make(map[int64]*ReferenceInfo),
+	}
+}
+
+// NewCheckedAST wraps an parsed AST and augments it with type and reference metadata.
+func NewCheckedAST(parsed *AST, typeMap map[int64]*types.Type, refMap map[int64]*ReferenceInfo) *AST {
+	return &AST{
+		expr:       parsed.Expr(),
+		sourceInfo: parsed.SourceInfo(),
+		typeMap:    typeMap,
+		refMap:     refMap,
+	}
+}
+
+// Copy creates a deep copy of the Expr and SourceInfo values in the input AST.
+//
+// Copies of the Expr value are generated using an internal default ExprFactory.
+func Copy(a *AST) *AST {
+	if a == nil {
+		return nil
+	}
+	e := defaultFactory.CopyExpr(a.expr)
+	if !a.IsChecked() {
+		return NewAST(e, CopySourceInfo(a.SourceInfo()))
+	}
+	typesCopy := make(map[int64]*types.Type, len(a.typeMap))
+	for id, t := range a.typeMap {
+		typesCopy[id] = t
+	}
+	refsCopy := make(map[int64]*ReferenceInfo, len(a.refMap))
+	for id, r := range a.refMap {
+		refsCopy[id] = r
+	}
+	return NewCheckedAST(NewAST(e, CopySourceInfo(a.SourceInfo())), typesCopy, refsCopy)
+}
+
+// MaxID returns the upper-bound, non-inclusive, of ids present within the AST's Expr value.
+func MaxID(a *AST) int64 {
+	visitor := &maxIDVisitor{maxID: 1}
+	PostOrderVisit(a.Expr(), visitor)
+	for id, call := range a.SourceInfo().MacroCalls() {
+		PostOrderVisit(call, visitor)
+		if id > visitor.maxID {
+			visitor.maxID = id + 1
+		}
+	}
+	return visitor.maxID + 1
+}
+
+// NewSourceInfo creates a simple SourceInfo object from an input common.Source value.
+func NewSourceInfo(src common.Source) *SourceInfo {
+	var lineOffsets []int32
+	var desc string
+	baseLine := int32(0)
+	baseCol := int32(0)
+	if src != nil {
+		desc = src.Description()
+		lineOffsets = src.LineOffsets()
+		// Determine whether the source metadata should be computed relative
+		// to a base line and column value. This can be determined by requesting
+		// the location for offset 0 from the source object.
+		if loc, found := src.OffsetLocation(0); found {
+			baseLine = int32(loc.Line()) - 1
+			baseCol = int32(loc.Column())
+		}
+	}
+	return &SourceInfo{
+		desc:         desc,
+		lines:        lineOffsets,
+		baseLine:     baseLine,
+		baseCol:      baseCol,
+		offsetRanges: make(map[int64]OffsetRange),
+		macroCalls:   make(map[int64]Expr),
+	}
+}
+
+// CopySourceInfo creates a deep copy of the MacroCalls within the input SourceInfo.
+//
+// Copies of macro Expr values are generated using an internal default ExprFactory.
+func CopySourceInfo(info *SourceInfo) *SourceInfo {
+	if info == nil {
+		return nil
+	}
+	rangesCopy := make(map[int64]OffsetRange, len(info.offsetRanges))
+	for id, off := range info.offsetRanges {
+		rangesCopy[id] = off
+	}
+	callsCopy := make(map[int64]Expr, len(info.macroCalls))
+	for id, call := range info.macroCalls {
+		callsCopy[id] = defaultFactory.CopyExpr(call)
+	}
+	return &SourceInfo{
+		syntax:       info.syntax,
+		desc:         info.desc,
+		lines:        info.lines,
+		baseLine:     info.baseLine,
+		baseCol:      info.baseCol,
+		offsetRanges: rangesCopy,
+		macroCalls:   callsCopy,
+	}
+}
+
+// SourceInfo records basic information about the expression as a textual input and
+// as a parsed expression value.
+type SourceInfo struct {
+	syntax       string
+	desc         string
+	lines        []int32
+	baseLine     int32
+	baseCol      int32
+	offsetRanges map[int64]OffsetRange
+	macroCalls   map[int64]Expr
+}
+
+// SyntaxVersion returns the syntax version associated with the text expression.
+func (s *SourceInfo) SyntaxVersion() string {
+	if s == nil {
+		return ""
+	}
+	return s.syntax
+}
+
+// Description provides information about where the expression came from.
+func (s *SourceInfo) Description() string {
+	if s == nil {
+		return ""
+	}
+	return s.desc
+}
+
+// LineOffsets returns a list of the 0-based character offsets in the input text where newlines appear.
+func (s *SourceInfo) LineOffsets() []int32 {
+	if s == nil {
+		return []int32{}
+	}
+	return s.lines
+}
+
+// MacroCalls returns a map of expression id to ast.Expr value where the id represents the expression
+// node where the macro was inserted into the AST, and the ast.Expr value represents the original call
+// signature which was replaced.
+func (s *SourceInfo) MacroCalls() map[int64]Expr {
+	if s == nil {
+		return map[int64]Expr{}
+	}
+	return s.macroCalls
+}
+
+// GetMacroCall returns the original ast.Expr value for the given expression if it was generated via
+// a macro replacement.
+//
+// Note, parsing options must be enabled to track macro calls before this method will return a value.
+func (s *SourceInfo) GetMacroCall(id int64) (Expr, bool) {
+	e, found := s.MacroCalls()[id]
+	return e, found
+}
+
+// SetMacroCall records a macro call at a specific location.
+func (s *SourceInfo) SetMacroCall(id int64, e Expr) {
+	if s != nil {
+		s.macroCalls[id] = e
+	}
+}
+
+// ClearMacroCall removes the macro call at the given expression id.
+func (s *SourceInfo) ClearMacroCall(id int64) {
+	if s != nil {
+		delete(s.macroCalls, id)
+	}
+}
+
+// OffsetRanges returns a map of expression id to OffsetRange values where the range indicates either:
+// the start and end position in the input stream where the expression occurs, or the start position
+// only. If the range only captures start position, the stop position of the range will be equal to
+// the start.
+func (s *SourceInfo) OffsetRanges() map[int64]OffsetRange {
+	if s == nil {
+		return map[int64]OffsetRange{}
+	}
+	return s.offsetRanges
+}
+
+// GetOffsetRange retrieves an OffsetRange for the given expression id if one exists.
+func (s *SourceInfo) GetOffsetRange(id int64) (OffsetRange, bool) {
+	if s == nil {
+		return OffsetRange{}, false
+	}
+	o, found := s.offsetRanges[id]
+	return o, found
+}
+
+// SetOffsetRange sets the OffsetRange for the given expression id.
+func (s *SourceInfo) SetOffsetRange(id int64, o OffsetRange) {
+	if s == nil {
+		return
+	}
+	s.offsetRanges[id] = o
+}
+
+// GetStartLocation calculates the human-readable 1-based line and 0-based column of the first character
+// of the expression node at the id.
+func (s *SourceInfo) GetStartLocation(id int64) common.Location {
+	if o, found := s.GetOffsetRange(id); found {
+		line := 1
+		col := int(o.Start)
+		for _, lineOffset := range s.LineOffsets() {
+			if lineOffset < o.Start {
+				line++
+				col = int(o.Start - lineOffset)
+			} else {
+				break
+			}
+		}
+		return common.NewLocation(line, col)
+	}
+	return common.NoLocation
+}
+
+// GetStopLocation calculates the human-readable 1-based line and 0-based column of the last character for
+// the expression node at the given id.
+//
+// If the SourceInfo was generated from a serialized protobuf representation, the stop location will
+// be identical to the start location for the expression.
+func (s *SourceInfo) GetStopLocation(id int64) common.Location {
+	if o, found := s.GetOffsetRange(id); found {
+		line := 1
+		col := int(o.Stop)
+		for _, lineOffset := range s.LineOffsets() {
+			if lineOffset < o.Stop {
+				line++
+				col = int(o.Stop - lineOffset)
+			} else {
+				break
+			}
+		}
+		return common.NewLocation(line, col)
+	}
+	return common.NoLocation
+}
+
+// ComputeOffset calculates the 0-based character offset from a 1-based line and 0-based column.
+func (s *SourceInfo) ComputeOffset(line, col int32) int32 {
+	if s != nil {
+		line = s.baseLine + line
+		col = s.baseCol + col
+	}
+	if line == 1 {
+		return col
+	}
+	if line < 1 || line > int32(len(s.LineOffsets())) {
+		return -1
+	}
+	offset := s.LineOffsets()[line-2]
+	return offset + col
+}
+
+// OffsetRange captures the start and stop positions of a section of text in the input expression.
+type OffsetRange struct {
+	Start int32
+	Stop  int32
 }
 
 // ReferenceInfo contains a CEL native representation of an identifier reference which may refer to
@@ -149,78 +436,21 @@ func (r *ReferenceInfo) Equals(other *ReferenceInfo) bool {
 	return true
 }
 
-// ReferenceInfoToReferenceExpr converts a ReferenceInfo instance to a protobuf Reference suitable for serialization.
-func ReferenceInfoToReferenceExpr(info *ReferenceInfo) (*exprpb.Reference, error) {
-	c, err := ValToConstant(info.Value)
-	if err != nil {
-		return nil, err
-	}
-	return &exprpb.Reference{
-		Name:       info.Name,
-		OverloadId: info.OverloadIDs,
-		Value:      c,
-	}, nil
+type maxIDVisitor struct {
+	maxID int64
+	*baseVisitor
 }
 
-// ReferenceExprToReferenceInfo converts a protobuf Reference into a CEL-native ReferenceInfo instance.
-func ReferenceExprToReferenceInfo(ref *exprpb.Reference) (*ReferenceInfo, error) {
-	v, err := ConstantToVal(ref.GetValue())
-	if err != nil {
-		return nil, err
+// VisitExpr updates the max identifier if the incoming expression id is greater than previously observed.
+func (v *maxIDVisitor) VisitExpr(e Expr) {
+	if v.maxID < e.ID() {
+		v.maxID = e.ID()
 	}
-	return &ReferenceInfo{
-		Name:        ref.GetName(),
-		OverloadIDs: ref.GetOverloadId(),
-		Value:       v,
-	}, nil
 }
 
-// ValToConstant converts a CEL-native ref.Val to a protobuf Constant.
-//
-// Only simple scalar types are supported by this method.
-func ValToConstant(v ref.Val) (*exprpb.Constant, error) {
-	if v == nil {
-		return nil, nil
+// VisitEntryExpr updates the max identifier if the incoming entry id is greater than previously observed.
+func (v *maxIDVisitor) VisitEntryExpr(e EntryExpr) {
+	if v.maxID < e.ID() {
+		v.maxID = e.ID()
 	}
-	switch v.Type() {
-	case types.BoolType:
-		return &exprpb.Constant{ConstantKind: &exprpb.Constant_BoolValue{BoolValue: v.Value().(bool)}}, nil
-	case types.BytesType:
-		return &exprpb.Constant{ConstantKind: &exprpb.Constant_BytesValue{BytesValue: v.Value().([]byte)}}, nil
-	case types.DoubleType:
-		return &exprpb.Constant{ConstantKind: &exprpb.Constant_DoubleValue{DoubleValue: v.Value().(float64)}}, nil
-	case types.IntType:
-		return &exprpb.Constant{ConstantKind: &exprpb.Constant_Int64Value{Int64Value: v.Value().(int64)}}, nil
-	case types.NullType:
-		return &exprpb.Constant{ConstantKind: &exprpb.Constant_NullValue{NullValue: structpb.NullValue_NULL_VALUE}}, nil
-	case types.StringType:
-		return &exprpb.Constant{ConstantKind: &exprpb.Constant_StringValue{StringValue: v.Value().(string)}}, nil
-	case types.UintType:
-		return &exprpb.Constant{ConstantKind: &exprpb.Constant_Uint64Value{Uint64Value: v.Value().(uint64)}}, nil
-	}
-	return nil, fmt.Errorf("unsupported constant kind: %v", v.Type())
-}
-
-// ConstantToVal converts a protobuf Constant to a CEL-native ref.Val.
-func ConstantToVal(c *exprpb.Constant) (ref.Val, error) {
-	if c == nil {
-		return nil, nil
-	}
-	switch c.GetConstantKind().(type) {
-	case *exprpb.Constant_BoolValue:
-		return types.Bool(c.GetBoolValue()), nil
-	case *exprpb.Constant_BytesValue:
-		return types.Bytes(c.GetBytesValue()), nil
-	case *exprpb.Constant_DoubleValue:
-		return types.Double(c.GetDoubleValue()), nil
-	case *exprpb.Constant_Int64Value:
-		return types.Int(c.GetInt64Value()), nil
-	case *exprpb.Constant_NullValue:
-		return types.NullValue, nil
-	case *exprpb.Constant_StringValue:
-		return types.String(c.GetStringValue()), nil
-	case *exprpb.Constant_Uint64Value:
-		return types.Uint(c.GetUint64Value()), nil
-	}
-	return nil, fmt.Errorf("unsupported constant kind: %v", c.GetConstantKind())
 }

vendor/github.com/google/cel-go/common/ast/conversion.go

@@ -0,0 +1,632 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ast
+
+import (
+	"fmt"
+
+	"github.com/google/cel-go/common/types"
+	"github.com/google/cel-go/common/types/ref"
+
+	structpb "google.golang.org/protobuf/types/known/structpb"
+
+	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
+)
+
+// ToProto converts an AST to a CheckedExpr protobouf.
+func ToProto(ast *AST) (*exprpb.CheckedExpr, error) {
+	refMap := make(map[int64]*exprpb.Reference, len(ast.ReferenceMap()))
+	for id, ref := range ast.ReferenceMap() {
+		r, err := ReferenceInfoToProto(ref)
+		if err != nil {
+			return nil, err
+		}
+		refMap[id] = r
+	}
+	typeMap := make(map[int64]*exprpb.Type, len(ast.TypeMap()))
+	for id, typ := range ast.TypeMap() {
+		t, err := types.TypeToExprType(typ)
+		if err != nil {
+			return nil, err
+		}
+		typeMap[id] = t
+	}
+	e, err := ExprToProto(ast.Expr())
+	if err != nil {
+		return nil, err
+	}
+	info, err := SourceInfoToProto(ast.SourceInfo())
+	if err != nil {
+		return nil, err
+	}
+	return &exprpb.CheckedExpr{
+		Expr:         e,
+		SourceInfo:   info,
+		ReferenceMap: refMap,
+		TypeMap:      typeMap,
+	}, nil
+}
+
+// ToAST converts a CheckedExpr protobuf to an AST instance.
+func ToAST(checked *exprpb.CheckedExpr) (*AST, error) {
+	refMap := make(map[int64]*ReferenceInfo, len(checked.GetReferenceMap()))
+	for id, ref := range checked.GetReferenceMap() {
+		r, err := ProtoToReferenceInfo(ref)
+		if err != nil {
+			return nil, err
+		}
+		refMap[id] = r
+	}
+	typeMap := make(map[int64]*types.Type, len(checked.GetTypeMap()))
+	for id, typ := range checked.GetTypeMap() {
+		t, err := types.ExprTypeToType(typ)
+		if err != nil {
+			return nil, err
+		}
+		typeMap[id] = t
+	}
+	info, err := ProtoToSourceInfo(checked.GetSourceInfo())
+	if err != nil {
+		return nil, err
+	}
+	root, err := ProtoToExpr(checked.GetExpr())
+	if err != nil {
+		return nil, err
+	}
+	ast := NewCheckedAST(NewAST(root, info), typeMap, refMap)
+	return ast, nil
+}
+
+// ProtoToExpr converts a protobuf Expr value to an ast.Expr value.
+func ProtoToExpr(e *exprpb.Expr) (Expr, error) {
+	factory := NewExprFactory()
+	return exprInternal(factory, e)
+}
+
+// ProtoToEntryExpr converts a protobuf struct/map entry to an ast.EntryExpr
+func ProtoToEntryExpr(e *exprpb.Expr_CreateStruct_Entry) (EntryExpr, error) {
+	factory := NewExprFactory()
+	switch e.GetKeyKind().(type) {
+	case *exprpb.Expr_CreateStruct_Entry_FieldKey:
+		return exprStructField(factory, e.GetId(), e)
+	case *exprpb.Expr_CreateStruct_Entry_MapKey:
+		return exprMapEntry(factory, e.GetId(), e)
+	}
+	return nil, fmt.Errorf("unsupported expr entry kind: %v", e)
+}
+
+func exprInternal(factory ExprFactory, e *exprpb.Expr) (Expr, error) {
+	id := e.GetId()
+	switch e.GetExprKind().(type) {
+	case *exprpb.Expr_CallExpr:
+		return exprCall(factory, id, e.GetCallExpr())
+	case *exprpb.Expr_ComprehensionExpr:
+		return exprComprehension(factory, id, e.GetComprehensionExpr())
+	case *exprpb.Expr_ConstExpr:
+		return exprLiteral(factory, id, e.GetConstExpr())
+	case *exprpb.Expr_IdentExpr:
+		return exprIdent(factory, id, e.GetIdentExpr())
+	case *exprpb.Expr_ListExpr:
+		return exprList(factory, id, e.GetListExpr())
+	case *exprpb.Expr_SelectExpr:
+		return exprSelect(factory, id, e.GetSelectExpr())
+	case *exprpb.Expr_StructExpr:
+		s := e.GetStructExpr()
+		if s.GetMessageName() != "" {
+			return exprStruct(factory, id, s)
+		}
+		return exprMap(factory, id, s)
+	}
+	return factory.NewUnspecifiedExpr(id), nil
+}
+
+func exprCall(factory ExprFactory, id int64, call *exprpb.Expr_Call) (Expr, error) {
+	var err error
+	args := make([]Expr, len(call.GetArgs()))
+	for i, a := range call.GetArgs() {
+		args[i], err = exprInternal(factory, a)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if call.GetTarget() == nil {
+		return factory.NewCall(id, call.GetFunction(), args...), nil
+	}
+
+	target, err := exprInternal(factory, call.GetTarget())
+	if err != nil {
+		return nil, err
+	}
+	return factory.NewMemberCall(id, call.GetFunction(), target, args...), nil
+}
+
+func exprComprehension(factory ExprFactory, id int64, comp *exprpb.Expr_Comprehension) (Expr, error) {
+	iterRange, err := exprInternal(factory, comp.GetIterRange())
+	if err != nil {
+		return nil, err
+	}
+	accuInit, err := exprInternal(factory, comp.GetAccuInit())
+	if err != nil {
+		return nil, err
+	}
+	loopCond, err := exprInternal(factory, comp.GetLoopCondition())
+	if err != nil {
+		return nil, err
+	}
+	loopStep, err := exprInternal(factory, comp.GetLoopStep())
+	if err != nil {
+		return nil, err
+	}
+	result, err := exprInternal(factory, comp.GetResult())
+	if err != nil {
+		return nil, err
+	}
+	return factory.NewComprehension(id,
+		iterRange,
+		comp.GetIterVar(),
+		comp.GetAccuVar(),
+		accuInit,
+		loopCond,
+		loopStep,
+		result), nil
+}
+
+func exprLiteral(factory ExprFactory, id int64, c *exprpb.Constant) (Expr, error) {
+	val, err := ConstantToVal(c)
+	if err != nil {
+		return nil, err
+	}
+	return factory.NewLiteral(id, val), nil
+}
+
+func exprIdent(factory ExprFactory, id int64, i *exprpb.Expr_Ident) (Expr, error) {
+	return factory.NewIdent(id, i.GetName()), nil
+}
+
+func exprList(factory ExprFactory, id int64, l *exprpb.Expr_CreateList) (Expr, error) {
+	elems := make([]Expr, len(l.GetElements()))
+	for i, e := range l.GetElements() {
+		elem, err := exprInternal(factory, e)
+		if err != nil {
+			return nil, err
+		}
+		elems[i] = elem
+	}
+	return factory.NewList(id, elems, l.GetOptionalIndices()), nil
+}
+
+func exprMap(factory ExprFactory, id int64, s *exprpb.Expr_CreateStruct) (Expr, error) {
+	entries := make([]EntryExpr, len(s.GetEntries()))
+	var err error
+	for i, entry := range s.GetEntries() {
+		entries[i], err = exprMapEntry(factory, entry.GetId(), entry)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return factory.NewMap(id, entries), nil
+}
+
+func exprMapEntry(factory ExprFactory, id int64, e *exprpb.Expr_CreateStruct_Entry) (EntryExpr, error) {
+	k, err := exprInternal(factory, e.GetMapKey())
+	if err != nil {
+		return nil, err
+	}
+	v, err := exprInternal(factory, e.GetValue())
+	if err != nil {
+		return nil, err
+	}
+	return factory.NewMapEntry(id, k, v, e.GetOptionalEntry()), nil
+}
+
+func exprSelect(factory ExprFactory, id int64, s *exprpb.Expr_Select) (Expr, error) {
+	op, err := exprInternal(factory, s.GetOperand())
+	if err != nil {
+		return nil, err
+	}
+	if s.GetTestOnly() {
+		return factory.NewPresenceTest(id, op, s.GetField()), nil
+	}
+	return factory.NewSelect(id, op, s.GetField()), nil
+}
+
+func exprStruct(factory ExprFactory, id int64, s *exprpb.Expr_CreateStruct) (Expr, error) {
+	fields := make([]EntryExpr, len(s.GetEntries()))
+	var err error
+	for i, field := range s.GetEntries() {
+		fields[i], err = exprStructField(factory, field.GetId(), field)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return factory.NewStruct(id, s.GetMessageName(), fields), nil
+}
+
+func exprStructField(factory ExprFactory, id int64, f *exprpb.Expr_CreateStruct_Entry) (EntryExpr, error) {
+	v, err := exprInternal(factory, f.GetValue())
+	if err != nil {
+		return nil, err
+	}
+	return factory.NewStructField(id, f.GetFieldKey(), v, f.GetOptionalEntry()), nil
+}
+
+// ExprToProto serializes an ast.Expr value to a protobuf Expr representation.
+func ExprToProto(e Expr) (*exprpb.Expr, error) {
+	if e == nil {
+		return &exprpb.Expr{}, nil
+	}
+	switch e.Kind() {
+	case CallKind:
+		return protoCall(e.ID(), e.AsCall())
+	case ComprehensionKind:
+		return protoComprehension(e.ID(), e.AsComprehension())
+	case IdentKind:
+		return protoIdent(e.ID(), e.AsIdent())
+	case ListKind:
+		return protoList(e.ID(), e.AsList())
+	case LiteralKind:
+		return protoLiteral(e.ID(), e.AsLiteral())
+	case MapKind:
+		return protoMap(e.ID(), e.AsMap())
+	case SelectKind:
+		return protoSelect(e.ID(), e.AsSelect())
+	case StructKind:
+		return protoStruct(e.ID(), e.AsStruct())
+	case UnspecifiedExprKind:
+		// Handle the case where a macro reference may be getting translated.
+		// A nested macro 'pointer' is a non-zero expression id with no kind set.
+		if e.ID() != 0 {
+			return &exprpb.Expr{Id: e.ID()}, nil
+		}
+		return &exprpb.Expr{}, nil
+	}
+	return nil, fmt.Errorf("unsupported expr kind: %v", e)
+}
+
+// EntryExprToProto converts an ast.EntryExpr to a protobuf CreateStruct entry
+func EntryExprToProto(e EntryExpr) (*exprpb.Expr_CreateStruct_Entry, error) {
+	switch e.Kind() {
+	case MapEntryKind:
+		return protoMapEntry(e.ID(), e.AsMapEntry())
+	case StructFieldKind:
+		return protoStructField(e.ID(), e.AsStructField())
+	case UnspecifiedEntryExprKind:
+		return &exprpb.Expr_CreateStruct_Entry{}, nil
+	}
+	return nil, fmt.Errorf("unsupported expr entry kind: %v", e)
+}
+
+func protoCall(id int64, call CallExpr) (*exprpb.Expr, error) {
+	var err error
+	var target *exprpb.Expr
+	if call.IsMemberFunction() {
+		target, err = ExprToProto(call.Target())
+		if err != nil {
+			return nil, err
+		}
+	}
+	callArgs := call.Args()
+	args := make([]*exprpb.Expr, len(callArgs))
+	for i, a := range callArgs {
+		args[i], err = ExprToProto(a)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_CallExpr{
+			CallExpr: &exprpb.Expr_Call{
+				Function: call.FunctionName(),
+				Target:   target,
+				Args:     args,
+			},
+		},
+	}, nil
+}
+
+func protoComprehension(id int64, comp ComprehensionExpr) (*exprpb.Expr, error) {
+	iterRange, err := ExprToProto(comp.IterRange())
+	if err != nil {
+		return nil, err
+	}
+	accuInit, err := ExprToProto(comp.AccuInit())
+	if err != nil {
+		return nil, err
+	}
+	loopCond, err := ExprToProto(comp.LoopCondition())
+	if err != nil {
+		return nil, err
+	}
+	loopStep, err := ExprToProto(comp.LoopStep())
+	if err != nil {
+		return nil, err
+	}
+	result, err := ExprToProto(comp.Result())
+	if err != nil {
+		return nil, err
+	}
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_ComprehensionExpr{
+			ComprehensionExpr: &exprpb.Expr_Comprehension{
+				IterVar:       comp.IterVar(),
+				IterRange:     iterRange,
+				AccuVar:       comp.AccuVar(),
+				AccuInit:      accuInit,
+				LoopCondition: loopCond,
+				LoopStep:      loopStep,
+				Result:        result,
+			},
+		},
+	}, nil
+}
+
+func protoIdent(id int64, name string) (*exprpb.Expr, error) {
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_IdentExpr{
+			IdentExpr: &exprpb.Expr_Ident{
+				Name: name,
+			},
+		},
+	}, nil
+}
+
+func protoList(id int64, list ListExpr) (*exprpb.Expr, error) {
+	var err error
+	elems := make([]*exprpb.Expr, list.Size())
+	for i, e := range list.Elements() {
+		elems[i], err = ExprToProto(e)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_ListExpr{
+			ListExpr: &exprpb.Expr_CreateList{
+				Elements:        elems,
+				OptionalIndices: list.OptionalIndices(),
+			},
+		},
+	}, nil
+}
+
+func protoLiteral(id int64, val ref.Val) (*exprpb.Expr, error) {
+	c, err := ValToConstant(val)
+	if err != nil {
+		return nil, err
+	}
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_ConstExpr{
+			ConstExpr: c,
+		},
+	}, nil
+}
+
+func protoMap(id int64, m MapExpr) (*exprpb.Expr, error) {
+	entries := make([]*exprpb.Expr_CreateStruct_Entry, len(m.Entries()))
+	var err error
+	for i, e := range m.Entries() {
+		entries[i], err = EntryExprToProto(e)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_StructExpr{
+			StructExpr: &exprpb.Expr_CreateStruct{
+				Entries: entries,
+			},
+		},
+	}, nil
+}
+
+func protoMapEntry(id int64, e MapEntry) (*exprpb.Expr_CreateStruct_Entry, error) {
+	k, err := ExprToProto(e.Key())
+	if err != nil {
+		return nil, err
+	}
+	v, err := ExprToProto(e.Value())
+	if err != nil {
+		return nil, err
+	}
+	return &exprpb.Expr_CreateStruct_Entry{
+		Id: id,
+		KeyKind: &exprpb.Expr_CreateStruct_Entry_MapKey{
+			MapKey: k,
+		},
+		Value:         v,
+		OptionalEntry: e.IsOptional(),
+	}, nil
+}
+
+func protoSelect(id int64, s SelectExpr) (*exprpb.Expr, error) {
+	op, err := ExprToProto(s.Operand())
+	if err != nil {
+		return nil, err
+	}
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_SelectExpr{
+			SelectExpr: &exprpb.Expr_Select{
+				Operand:  op,
+				Field:    s.FieldName(),
+				TestOnly: s.IsTestOnly(),
+			},
+		},
+	}, nil
+}
+
+func protoStruct(id int64, s StructExpr) (*exprpb.Expr, error) {
+	entries := make([]*exprpb.Expr_CreateStruct_Entry, len(s.Fields()))
+	var err error
+	for i, e := range s.Fields() {
+		entries[i], err = EntryExprToProto(e)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &exprpb.Expr{
+		Id: id,
+		ExprKind: &exprpb.Expr_StructExpr{
+			StructExpr: &exprpb.Expr_CreateStruct{
+				MessageName: s.TypeName(),
+				Entries:     entries,
+			},
+		},
+	}, nil
+}
+
+func protoStructField(id int64, f StructField) (*exprpb.Expr_CreateStruct_Entry, error) {
+	v, err := ExprToProto(f.Value())
+	if err != nil {
+		return nil, err
+	}
+	return &exprpb.Expr_CreateStruct_Entry{
+		Id: id,
+		KeyKind: &exprpb.Expr_CreateStruct_Entry_FieldKey{
+			FieldKey: f.Name(),
+		},
+		Value:         v,
+		OptionalEntry: f.IsOptional(),
+	}, nil
+}
+
+// SourceInfoToProto serializes an ast.SourceInfo value to a protobuf SourceInfo object.
+func SourceInfoToProto(info *SourceInfo) (*exprpb.SourceInfo, error) {
+	if info == nil {
+		return &exprpb.SourceInfo{}, nil
+	}
+	sourceInfo := &exprpb.SourceInfo{
+		SyntaxVersion: info.SyntaxVersion(),
+		Location:      info.Description(),
+		LineOffsets:   info.LineOffsets(),
+		Positions:     make(map[int64]int32, len(info.OffsetRanges())),
+		MacroCalls:    make(map[int64]*exprpb.Expr, len(info.MacroCalls())),
+	}
+	for id, offset := range info.OffsetRanges() {
+		sourceInfo.Positions[id] = offset.Start
+	}
+	for id, e := range info.MacroCalls() {
+		call, err := ExprToProto(e)
+		if err != nil {
+			return nil, err
+		}
+		sourceInfo.MacroCalls[id] = call
+	}
+	return sourceInfo, nil
+}
+
+// ProtoToSourceInfo deserializes the protobuf into a native SourceInfo value.
+func ProtoToSourceInfo(info *exprpb.SourceInfo) (*SourceInfo, error) {
+	sourceInfo := &SourceInfo{
+		syntax:       info.GetSyntaxVersion(),
+		desc:         info.GetLocation(),
+		lines:        info.GetLineOffsets(),
+		offsetRanges: make(map[int64]OffsetRange, len(info.GetPositions())),
+		macroCalls:   make(map[int64]Expr, len(info.GetMacroCalls())),
+	}
+	for id, offset := range info.GetPositions() {
+		sourceInfo.SetOffsetRange(id, OffsetRange{Start: offset, Stop: offset})
+	}
+	for id, e := range info.GetMacroCalls() {
+		call, err := ProtoToExpr(e)
+		if err != nil {
+			return nil, err
+		}
+		sourceInfo.SetMacroCall(id, call)
+	}
+	return sourceInfo, nil
+}
+
+// ReferenceInfoToProto converts a ReferenceInfo instance to a protobuf Reference suitable for serialization.
+func ReferenceInfoToProto(info *ReferenceInfo) (*exprpb.Reference, error) {
+	c, err := ValToConstant(info.Value)
+	if err != nil {
+		return nil, err
+	}
+	return &exprpb.Reference{
+		Name:       info.Name,
+		OverloadId: info.OverloadIDs,
+		Value:      c,
+	}, nil
+}
+
+// ProtoToReferenceInfo converts a protobuf Reference into a CEL-native ReferenceInfo instance.
+func ProtoToReferenceInfo(ref *exprpb.Reference) (*ReferenceInfo, error) {
+	v, err := ConstantToVal(ref.GetValue())
+	if err != nil {
+		return nil, err
+	}
+	return &ReferenceInfo{
+		Name:        ref.GetName(),
+		OverloadIDs: ref.GetOverloadId(),
+		Value:       v,
+	}, nil
+}
+
+// ValToConstant converts a CEL-native ref.Val to a protobuf Constant.
+//
+// Only simple scalar types are supported by this method.
+func ValToConstant(v ref.Val) (*exprpb.Constant, error) {
+	if v == nil {
+		return nil, nil
+	}
+	switch v.Type() {
+	case types.BoolType:
+		return &exprpb.Constant{ConstantKind: &exprpb.Constant_BoolValue{BoolValue: v.Value().(bool)}}, nil
+	case types.BytesType:
+		return &exprpb.Constant{ConstantKind: &exprpb.Constant_BytesValue{BytesValue: v.Value().([]byte)}}, nil
+	case types.DoubleType:
+		return &exprpb.Constant{ConstantKind: &exprpb.Constant_DoubleValue{DoubleValue: v.Value().(float64)}}, nil
+	case types.IntType:
+		return &exprpb.Constant{ConstantKind: &exprpb.Constant_Int64Value{Int64Value: v.Value().(int64)}}, nil
+	case types.NullType:
+		return &exprpb.Constant{ConstantKind: &exprpb.Constant_NullValue{NullValue: structpb.NullValue_NULL_VALUE}}, nil
+	case types.StringType:
+		return &exprpb.Constant{ConstantKind: &exprpb.Constant_StringValue{StringValue: v.Value().(string)}}, nil
+	case types.UintType:
+		return &exprpb.Constant{ConstantKind: &exprpb.Constant_Uint64Value{Uint64Value: v.Value().(uint64)}}, nil
+	}
+	return nil, fmt.Errorf("unsupported constant kind: %v", v.Type())
+}
+
+// ConstantToVal converts a protobuf Constant to a CEL-native ref.Val.
+func ConstantToVal(c *exprpb.Constant) (ref.Val, error) {
+	if c == nil {
+		return nil, nil
+	}
+	switch c.GetConstantKind().(type) {
+	case *exprpb.Constant_BoolValue:
+		return types.Bool(c.GetBoolValue()), nil
+	case *exprpb.Constant_BytesValue:
+		return types.Bytes(c.GetBytesValue()), nil
+	case *exprpb.Constant_DoubleValue:
+		return types.Double(c.GetDoubleValue()), nil
+	case *exprpb.Constant_Int64Value:
+		return types.Int(c.GetInt64Value()), nil
+	case *exprpb.Constant_NullValue:
+		return types.NullValue, nil
+	case *exprpb.Constant_StringValue:
+		return types.String(c.GetStringValue()), nil
+	case *exprpb.Constant_Uint64Value:
+		return types.Uint(c.GetUint64Value()), nil
+	}
+	return nil, fmt.Errorf("unsupported constant kind: %v", c.GetConstantKind())
+}

vendor/github.com/google/cel-go/common/ast/factory.go

@@ -0,0 +1,303 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ast
+
+import "github.com/google/cel-go/common/types/ref"
+
+// ExprFactory interfaces defines a set of methods necessary for building native expression values.
+type ExprFactory interface {
+	// CopyExpr creates a deep copy of the input Expr value.
+	CopyExpr(Expr) Expr
+
+	// CopyEntryExpr creates a deep copy of the input EntryExpr value.
+	CopyEntryExpr(EntryExpr) EntryExpr
+
+	// NewCall creates an Expr value representing a global function call.
+	NewCall(id int64, function string, args ...Expr) Expr
+
+	// NewComprehension creates an Expr value representing a comprehension over a value range.
+	NewComprehension(id int64, iterRange Expr, iterVar, accuVar string, accuInit, loopCondition, loopStep, result Expr) Expr
+
+	// NewMemberCall creates an Expr value representing a member function call.
+	NewMemberCall(id int64, function string, receiver Expr, args ...Expr) Expr
+
+	// NewIdent creates an Expr value representing an identifier.
+	NewIdent(id int64, name string) Expr
+
+	// NewAccuIdent creates an Expr value representing an accumulator identifier within a
+	//comprehension.
+	NewAccuIdent(id int64) Expr
+
+	// NewLiteral creates an Expr value representing a literal value, such as a string or integer.
+	NewLiteral(id int64, value ref.Val) Expr
+
+	// NewList creates an Expr value representing a list literal expression with optional indices.
+	//
+	// Optional indicies will typically be empty unless the CEL optional types are enabled.
+	NewList(id int64, elems []Expr, optIndices []int32) Expr
+
+	// NewMap creates an Expr value representing a map literal expression
+	NewMap(id int64, entries []EntryExpr) Expr
+
+	// NewMapEntry creates a MapEntry with a given key, value, and a flag indicating whether
+	// the key is optionally set.
+	NewMapEntry(id int64, key, value Expr, isOptional bool) EntryExpr
+
+	// NewPresenceTest creates an Expr representing a field presence test on an operand expression.
+	NewPresenceTest(id int64, operand Expr, field string) Expr
+
+	// NewSelect creates an Expr representing a field selection on an operand expression.
+	NewSelect(id int64, operand Expr, field string) Expr
+
+	// NewStruct creates an Expr value representing a struct literal with a given type name and a
+	// set of field initializers.
+	NewStruct(id int64, typeName string, fields []EntryExpr) Expr
+
+	// NewStructField creates a StructField with a given field name, value, and a flag indicating
+	// whether the field is optionally set.
+	NewStructField(id int64, field string, value Expr, isOptional bool) EntryExpr
+
+	// NewUnspecifiedExpr creates an empty expression node.
+	NewUnspecifiedExpr(id int64) Expr
+
+	isExprFactory()
+}
+
+type baseExprFactory struct{}
+
+// NewExprFactory creates an ExprFactory instance.
+func NewExprFactory() ExprFactory {
+	return &baseExprFactory{}
+}
+
+func (fac *baseExprFactory) NewCall(id int64, function string, args ...Expr) Expr {
+	if len(args) == 0 {
+		args = []Expr{}
+	}
+	return fac.newExpr(
+		id,
+		&baseCallExpr{
+			function: function,
+			target:   nilExpr,
+			args:     args,
+			isMember: false,
+		})
+}
+
+func (fac *baseExprFactory) NewMemberCall(id int64, function string, target Expr, args ...Expr) Expr {
+	if len(args) == 0 {
+		args = []Expr{}
+	}
+	return fac.newExpr(
+		id,
+		&baseCallExpr{
+			function: function,
+			target:   target,
+			args:     args,
+			isMember: true,
+		})
+}
+
+func (fac *baseExprFactory) NewComprehension(id int64, iterRange Expr, iterVar, accuVar string, accuInit, loopCond, loopStep, result Expr) Expr {
+	return fac.newExpr(
+		id,
+		&baseComprehensionExpr{
+			iterRange: iterRange,
+			iterVar:   iterVar,
+			accuVar:   accuVar,
+			accuInit:  accuInit,
+			loopCond:  loopCond,
+			loopStep:  loopStep,
+			result:    result,
+		})
+}
+
+func (fac *baseExprFactory) NewIdent(id int64, name string) Expr {
+	return fac.newExpr(id, baseIdentExpr(name))
+}
+
+func (fac *baseExprFactory) NewAccuIdent(id int64) Expr {
+	return fac.NewIdent(id, "__result__")
+}
+
+func (fac *baseExprFactory) NewLiteral(id int64, value ref.Val) Expr {
+	return fac.newExpr(id, &baseLiteral{Val: value})
+}
+
+func (fac *baseExprFactory) NewList(id int64, elems []Expr, optIndices []int32) Expr {
+	optIndexMap := make(map[int32]struct{}, len(optIndices))
+	for _, idx := range optIndices {
+		optIndexMap[idx] = struct{}{}
+	}
+	return fac.newExpr(id,
+		&baseListExpr{
+			elements:    elems,
+			optIndices:  optIndices,
+			optIndexMap: optIndexMap,
+		})
+}
+
+func (fac *baseExprFactory) NewMap(id int64, entries []EntryExpr) Expr {
+	return fac.newExpr(id, &baseMapExpr{entries: entries})
+}
+
+func (fac *baseExprFactory) NewMapEntry(id int64, key, value Expr, isOptional bool) EntryExpr {
+	return fac.newEntryExpr(
+		id,
+		&baseMapEntry{
+			key:        key,
+			value:      value,
+			isOptional: isOptional,
+		})
+}
+
+func (fac *baseExprFactory) NewPresenceTest(id int64, operand Expr, field string) Expr {
+	return fac.newExpr(
+		id,
+		&baseSelectExpr{
+			operand:  operand,
+			field:    field,
+			testOnly: true,
+		})
+}
+
+func (fac *baseExprFactory) NewSelect(id int64, operand Expr, field string) Expr {
+	return fac.newExpr(
+		id,
+		&baseSelectExpr{
+			operand: operand,
+			field:   field,
+		})
+}
+
+func (fac *baseExprFactory) NewStruct(id int64, typeName string, fields []EntryExpr) Expr {
+	return fac.newExpr(
+		id,
+		&baseStructExpr{
+			typeName: typeName,
+			fields:   fields,
+		})
+}
+
+func (fac *baseExprFactory) NewStructField(id int64, field string, value Expr, isOptional bool) EntryExpr {
+	return fac.newEntryExpr(
+		id,
+		&baseStructField{
+			field:      field,
+			value:      value,
+			isOptional: isOptional,
+		})
+}
+
+func (fac *baseExprFactory) NewUnspecifiedExpr(id int64) Expr {
+	return fac.newExpr(id, nil)
+}
+
+func (fac *baseExprFactory) CopyExpr(e Expr) Expr {
+	// unwrap navigable expressions to avoid unnecessary allocations during copying.
+	if nav, ok := e.(*navigableExprImpl); ok {
+		e = nav.Expr
+	}
+	switch e.Kind() {
+	case CallKind:
+		c := e.AsCall()
+		argsCopy := make([]Expr, len(c.Args()))
+		for i, arg := range c.Args() {
+			argsCopy[i] = fac.CopyExpr(arg)
+		}
+		if !c.IsMemberFunction() {
+			return fac.NewCall(e.ID(), c.FunctionName(), argsCopy...)
+		}
+		return fac.NewMemberCall(e.ID(), c.FunctionName(), fac.CopyExpr(c.Target()), argsCopy...)
+	case ComprehensionKind:
+		compre := e.AsComprehension()
+		return fac.NewComprehension(e.ID(),
+			fac.CopyExpr(compre.IterRange()),
+			compre.IterVar(),
+			compre.AccuVar(),
+			fac.CopyExpr(compre.AccuInit()),
+			fac.CopyExpr(compre.LoopCondition()),
+			fac.CopyExpr(compre.LoopStep()),
+			fac.CopyExpr(compre.Result()))
+	case IdentKind:
+		return fac.NewIdent(e.ID(), e.AsIdent())
+	case ListKind:
+		l := e.AsList()
+		elemsCopy := make([]Expr, l.Size())
+		for i, elem := range l.Elements() {
+			elemsCopy[i] = fac.CopyExpr(elem)
+		}
+		return fac.NewList(e.ID(), elemsCopy, l.OptionalIndices())
+	case LiteralKind:
+		return fac.NewLiteral(e.ID(), e.AsLiteral())
+	case MapKind:
+		m := e.AsMap()
+		entriesCopy := make([]EntryExpr, m.Size())
+		for i, entry := range m.Entries() {
+			entriesCopy[i] = fac.CopyEntryExpr(entry)
+		}
+		return fac.NewMap(e.ID(), entriesCopy)
+	case SelectKind:
+		s := e.AsSelect()
+		if s.IsTestOnly() {
+			return fac.NewPresenceTest(e.ID(), fac.CopyExpr(s.Operand()), s.FieldName())
+		}
+		return fac.NewSelect(e.ID(), fac.CopyExpr(s.Operand()), s.FieldName())
+	case StructKind:
+		s := e.AsStruct()
+		fieldsCopy := make([]EntryExpr, len(s.Fields()))
+		for i, field := range s.Fields() {
+			fieldsCopy[i] = fac.CopyEntryExpr(field)
+		}
+		return fac.NewStruct(e.ID(), s.TypeName(), fieldsCopy)
+	default:
+		return fac.NewUnspecifiedExpr(e.ID())
+	}
+}
+
+func (fac *baseExprFactory) CopyEntryExpr(e EntryExpr) EntryExpr {
+	switch e.Kind() {
+	case MapEntryKind:
+		entry := e.AsMapEntry()
+		return fac.NewMapEntry(e.ID(),
+			fac.CopyExpr(entry.Key()), fac.CopyExpr(entry.Value()), entry.IsOptional())
+	case StructFieldKind:
+		field := e.AsStructField()
+		return fac.NewStructField(e.ID(),
+			field.Name(), fac.CopyExpr(field.Value()), field.IsOptional())
+	default:
+		return fac.newEntryExpr(e.ID(), nil)
+	}
+}
+
+func (*baseExprFactory) isExprFactory() {}
+
+func (fac *baseExprFactory) newExpr(id int64, e exprKindCase) Expr {
+	return &expr{
+		id:           id,
+		exprKindCase: e,
+	}
+}
+
+func (fac *baseExprFactory) newEntryExpr(id int64, e entryExprKindCase) EntryExpr {
+	return &entryExpr{
+		id:                id,
+		entryExprKindCase: e,
+	}
+}
+
+var (
+	defaultFactory = &baseExprFactory{}
+)

vendor/github.com/google/cel-go/common/ast/navigable.go

@@ -0,0 +1,652 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ast
+
+import (
+	"github.com/google/cel-go/common/types"
+	"github.com/google/cel-go/common/types/ref"
+)
+
+// NavigableExpr represents the base navigable expression value with methods to inspect the
+// parent and child expressions.
+type NavigableExpr interface {
+	Expr
+
+	// Type of the expression.
+	//
+	// If the expression is type-checked, the type check metadata is returned. If the expression
+	// has not been type-checked, the types.DynType value is returned.
+	Type() *types.Type
+
+	// Parent returns the parent expression node, if one exists.
+	Parent() (NavigableExpr, bool)
+
+	// Children returns a list of child expression nodes.
+	Children() []NavigableExpr
+
+	// Depth indicates the depth in the expression tree.
+	//
+	// The root expression has depth 0.
+	Depth() int
+}
+
+// NavigateAST converts an AST to a NavigableExpr
+func NavigateAST(ast *AST) NavigableExpr {
+	return NavigateExpr(ast, ast.Expr())
+}
+
+// NavigateExpr creates a NavigableExpr whose type information is backed by the input AST.
+//
+// If the expression is already a NavigableExpr, the parent and depth information will be
+// propagated on the new NavigableExpr value; otherwise, the expr value will be treated
+// as though it is the root of the expression graph with a depth of 0.
+func NavigateExpr(ast *AST, expr Expr) NavigableExpr {
+	depth := 0
+	var parent NavigableExpr = nil
+	if nav, ok := expr.(NavigableExpr); ok {
+		depth = nav.Depth()
+		parent, _ = nav.Parent()
+	}
+	return newNavigableExpr(ast, parent, expr, depth)
+}
+
+// ExprMatcher takes a NavigableExpr in and indicates whether the value is a match.
+//
+// This function type should be use with the `Match` and `MatchList` calls.
+type ExprMatcher func(NavigableExpr) bool
+
+// ConstantValueMatcher returns an ExprMatcher which will return true if the input NavigableExpr
+// is comprised of all constant values, such as a simple literal or even list and map literal.
+func ConstantValueMatcher() ExprMatcher {
+	return matchIsConstantValue
+}
+
+// KindMatcher returns an ExprMatcher which will return true if the input NavigableExpr.Kind() matches
+// the specified `kind`.
+func KindMatcher(kind ExprKind) ExprMatcher {
+	return func(e NavigableExpr) bool {
+		return e.Kind() == kind
+	}
+}
+
+// FunctionMatcher returns an ExprMatcher which will match NavigableExpr nodes of CallKind type whose
+// function name is equal to `funcName`.
+func FunctionMatcher(funcName string) ExprMatcher {
+	return func(e NavigableExpr) bool {
+		if e.Kind() != CallKind {
+			return false
+		}
+		return e.AsCall().FunctionName() == funcName
+	}
+}
+
+// AllMatcher returns true for all descendants of a NavigableExpr, effectively flattening them into a list.
+//
+// Such a result would work well with subsequent MatchList calls.
+func AllMatcher() ExprMatcher {
+	return func(NavigableExpr) bool {
+		return true
+	}
+}
+
+// MatchDescendants takes a NavigableExpr and ExprMatcher and produces a list of NavigableExpr values
+// matching the input criteria in post-order (bottom up).
+func MatchDescendants(expr NavigableExpr, matcher ExprMatcher) []NavigableExpr {
+	matches := []NavigableExpr{}
+	navVisitor := &baseVisitor{
+		visitExpr: func(e Expr) {
+			nav := e.(NavigableExpr)
+			if matcher(nav) {
+				matches = append(matches, nav)
+			}
+		},
+	}
+	visit(expr, navVisitor, postOrder, 0, 0)
+	return matches
+}
+
+// MatchSubset applies an ExprMatcher to a list of NavigableExpr values and their descendants, producing a
+// subset of NavigableExpr values which match.
+func MatchSubset(exprs []NavigableExpr, matcher ExprMatcher) []NavigableExpr {
+	matches := []NavigableExpr{}
+	navVisitor := &baseVisitor{
+		visitExpr: func(e Expr) {
+			nav := e.(NavigableExpr)
+			if matcher(nav) {
+				matches = append(matches, nav)
+			}
+		},
+	}
+	for _, expr := range exprs {
+		visit(expr, navVisitor, postOrder, 0, 1)
+	}
+	return matches
+}
+
+// Visitor defines an object for visiting Expr and EntryExpr nodes within an expression graph.
+type Visitor interface {
+	// VisitExpr visits the input expression.
+	VisitExpr(Expr)
+
+	// VisitEntryExpr visits the input entry expression, i.e. a struct field or map entry.
+	VisitEntryExpr(EntryExpr)
+}
+
+type baseVisitor struct {
+	visitExpr      func(Expr)
+	visitEntryExpr func(EntryExpr)
+}
+
+// VisitExpr visits the Expr if the internal expr visitor has been configured.
+func (v *baseVisitor) VisitExpr(e Expr) {
+	if v.visitExpr != nil {
+		v.visitExpr(e)
+	}
+}
+
+// VisitEntryExpr visits the entry if the internal expr entry visitor has been configured.
+func (v *baseVisitor) VisitEntryExpr(e EntryExpr) {
+	if v.visitEntryExpr != nil {
+		v.visitEntryExpr(e)
+	}
+}
+
+// NewExprVisitor creates a visitor which only visits expression nodes.
+func NewExprVisitor(v func(Expr)) Visitor {
+	return &baseVisitor{
+		visitExpr:      v,
+		visitEntryExpr: nil,
+	}
+}
+
+// PostOrderVisit walks the expression graph and calls the visitor in post-order (bottom-up).
+func PostOrderVisit(expr Expr, visitor Visitor) {
+	visit(expr, visitor, postOrder, 0, 0)
+}
+
+// PreOrderVisit walks the expression graph and calls the visitor in pre-order (top-down).
+func PreOrderVisit(expr Expr, visitor Visitor) {
+	visit(expr, visitor, preOrder, 0, 0)
+}
+
+type visitOrder int
+
+const (
+	preOrder = iota + 1
+	postOrder
+)
+
+// TODO: consider exposing a way to configure a limit for the max visit depth.
+// It's possible that we could want to configure this on the NewExprVisitor()
+// and through MatchDescendents() / MaxID().
+func visit(expr Expr, visitor Visitor, order visitOrder, depth, maxDepth int) {
+	if maxDepth > 0 && depth == maxDepth {
+		return
+	}
+	if order == preOrder {
+		visitor.VisitExpr(expr)
+	}
+	switch expr.Kind() {
+	case CallKind:
+		c := expr.AsCall()
+		if c.IsMemberFunction() {
+			visit(c.Target(), visitor, order, depth+1, maxDepth)
+		}
+		for _, arg := range c.Args() {
+			visit(arg, visitor, order, depth+1, maxDepth)
+		}
+	case ComprehensionKind:
+		c := expr.AsComprehension()
+		visit(c.IterRange(), visitor, order, depth+1, maxDepth)
+		visit(c.AccuInit(), visitor, order, depth+1, maxDepth)
+		visit(c.LoopCondition(), visitor, order, depth+1, maxDepth)
+		visit(c.LoopStep(), visitor, order, depth+1, maxDepth)
+		visit(c.Result(), visitor, order, depth+1, maxDepth)
+	case ListKind:
+		l := expr.AsList()
+		for _, elem := range l.Elements() {
+			visit(elem, visitor, order, depth+1, maxDepth)
+		}
+	case MapKind:
+		m := expr.AsMap()
+		for _, e := range m.Entries() {
+			if order == preOrder {
+				visitor.VisitEntryExpr(e)
+			}
+			entry := e.AsMapEntry()
+			visit(entry.Key(), visitor, order, depth+1, maxDepth)
+			visit(entry.Value(), visitor, order, depth+1, maxDepth)
+			if order == postOrder {
+				visitor.VisitEntryExpr(e)
+			}
+		}
+	case SelectKind:
+		visit(expr.AsSelect().Operand(), visitor, order, depth+1, maxDepth)
+	case StructKind:
+		s := expr.AsStruct()
+		for _, f := range s.Fields() {
+			visitor.VisitEntryExpr(f)
+			visit(f.AsStructField().Value(), visitor, order, depth+1, maxDepth)
+		}
+	}
+	if order == postOrder {
+		visitor.VisitExpr(expr)
+	}
+}
+
+func matchIsConstantValue(e NavigableExpr) bool {
+	if e.Kind() == LiteralKind {
+		return true
+	}
+	if e.Kind() == StructKind || e.Kind() == MapKind || e.Kind() == ListKind {
+		for _, child := range e.Children() {
+			if !matchIsConstantValue(child) {
+				return false
+			}
+		}
+		return true
+	}
+	return false
+}
+
+func newNavigableExpr(ast *AST, parent NavigableExpr, expr Expr, depth int) NavigableExpr {
+	// Reduce navigable expression nesting by unwrapping the embedded Expr value.
+	if nav, ok := expr.(*navigableExprImpl); ok {
+		expr = nav.Expr
+	}
+	nav := &navigableExprImpl{
+		Expr:           expr,
+		depth:          depth,
+		ast:            ast,
+		parent:         parent,
+		createChildren: getChildFactory(expr),
+	}
+	return nav
+}
+
+type navigableExprImpl struct {
+	Expr
+	depth          int
+	ast            *AST
+	parent         NavigableExpr
+	createChildren childFactory
+}
+
+func (nav *navigableExprImpl) Parent() (NavigableExpr, bool) {
+	if nav.parent != nil {
+		return nav.parent, true
+	}
+	return nil, false
+}
+
+func (nav *navigableExprImpl) ID() int64 {
+	return nav.Expr.ID()
+}
+
+func (nav *navigableExprImpl) Kind() ExprKind {
+	return nav.Expr.Kind()
+}
+
+func (nav *navigableExprImpl) Type() *types.Type {
+	return nav.ast.GetType(nav.ID())
+}
+
+func (nav *navigableExprImpl) Children() []NavigableExpr {
+	return nav.createChildren(nav)
+}
+
+func (nav *navigableExprImpl) Depth() int {
+	return nav.depth
+}
+
+func (nav *navigableExprImpl) AsCall() CallExpr {
+	return navigableCallImpl{navigableExprImpl: nav}
+}
+
+func (nav *navigableExprImpl) AsComprehension() ComprehensionExpr {
+	return navigableComprehensionImpl{navigableExprImpl: nav}
+}
+
+func (nav *navigableExprImpl) AsIdent() string {
+	return nav.Expr.AsIdent()
+}
+
+func (nav *navigableExprImpl) AsList() ListExpr {
+	return navigableListImpl{navigableExprImpl: nav}
+}
+
+func (nav *navigableExprImpl) AsLiteral() ref.Val {
+	return nav.Expr.AsLiteral()
+}
+
+func (nav *navigableExprImpl) AsMap() MapExpr {
+	return navigableMapImpl{navigableExprImpl: nav}
+}
+
+func (nav *navigableExprImpl) AsSelect() SelectExpr {
+	return navigableSelectImpl{navigableExprImpl: nav}
+}
+
+func (nav *navigableExprImpl) AsStruct() StructExpr {
+	return navigableStructImpl{navigableExprImpl: nav}
+}
+
+func (nav *navigableExprImpl) createChild(e Expr) NavigableExpr {
+	return newNavigableExpr(nav.ast, nav, e, nav.depth+1)
+}
+
+func (nav *navigableExprImpl) isExpr() {}
+
+type navigableCallImpl struct {
+	*navigableExprImpl
+}
+
+func (call navigableCallImpl) FunctionName() string {
+	return call.Expr.AsCall().FunctionName()
+}
+
+func (call navigableCallImpl) IsMemberFunction() bool {
+	return call.Expr.AsCall().IsMemberFunction()
+}
+
+func (call navigableCallImpl) Target() Expr {
+	t := call.Expr.AsCall().Target()
+	if t != nil {
+		return call.createChild(t)
+	}
+	return nil
+}
+
+func (call navigableCallImpl) Args() []Expr {
+	args := call.Expr.AsCall().Args()
+	navArgs := make([]Expr, len(args))
+	for i, a := range args {
+		navArgs[i] = call.createChild(a)
+	}
+	return navArgs
+}
+
+type navigableComprehensionImpl struct {
+	*navigableExprImpl
+}
+
+func (comp navigableComprehensionImpl) IterRange() Expr {
+	return comp.createChild(comp.Expr.AsComprehension().IterRange())
+}
+
+func (comp navigableComprehensionImpl) IterVar() string {
+	return comp.Expr.AsComprehension().IterVar()
+}
+
+func (comp navigableComprehensionImpl) AccuVar() string {
+	return comp.Expr.AsComprehension().AccuVar()
+}
+
+func (comp navigableComprehensionImpl) AccuInit() Expr {
+	return comp.createChild(comp.Expr.AsComprehension().AccuInit())
+}
+
+func (comp navigableComprehensionImpl) LoopCondition() Expr {
+	return comp.createChild(comp.Expr.AsComprehension().LoopCondition())
+}
+
+func (comp navigableComprehensionImpl) LoopStep() Expr {
+	return comp.createChild(comp.Expr.AsComprehension().LoopStep())
+}
+
+func (comp navigableComprehensionImpl) Result() Expr {
+	return comp.createChild(comp.Expr.AsComprehension().Result())
+}
+
+type navigableListImpl struct {
+	*navigableExprImpl
+}
+
+func (l navigableListImpl) Elements() []Expr {
+	pbElems := l.Expr.AsList().Elements()
+	elems := make([]Expr, len(pbElems))
+	for i := 0; i < len(pbElems); i++ {
+		elems[i] = l.createChild(pbElems[i])
+	}
+	return elems
+}
+
+func (l navigableListImpl) IsOptional(index int32) bool {
+	return l.Expr.AsList().IsOptional(index)
+}
+
+func (l navigableListImpl) OptionalIndices() []int32 {
+	return l.Expr.AsList().OptionalIndices()
+}
+
+func (l navigableListImpl) Size() int {
+	return l.Expr.AsList().Size()
+}
+
+type navigableMapImpl struct {
+	*navigableExprImpl
+}
+
+func (m navigableMapImpl) Entries() []EntryExpr {
+	mapExpr := m.Expr.AsMap()
+	entries := make([]EntryExpr, len(mapExpr.Entries()))
+	for i, e := range mapExpr.Entries() {
+		entry := e.AsMapEntry()
+		entries[i] = &entryExpr{
+			id: e.ID(),
+			entryExprKindCase: navigableEntryImpl{
+				key:   m.createChild(entry.Key()),
+				val:   m.createChild(entry.Value()),
+				isOpt: entry.IsOptional(),
+			},
+		}
+	}
+	return entries
+}
+
+func (m navigableMapImpl) Size() int {
+	return m.Expr.AsMap().Size()
+}
+
+type navigableEntryImpl struct {
+	key   NavigableExpr
+	val   NavigableExpr
+	isOpt bool
+}
+
+func (e navigableEntryImpl) Kind() EntryExprKind {
+	return MapEntryKind
+}
+
+func (e navigableEntryImpl) Key() Expr {
+	return e.key
+}
+
+func (e navigableEntryImpl) Value() Expr {
+	return e.val
+}
+
+func (e navigableEntryImpl) IsOptional() bool {
+	return e.isOpt
+}
+
+func (e navigableEntryImpl) renumberIDs(IDGenerator) {}
+
+func (e navigableEntryImpl) isEntryExpr() {}
+
+type navigableSelectImpl struct {
+	*navigableExprImpl
+}
+
+func (sel navigableSelectImpl) FieldName() string {
+	return sel.Expr.AsSelect().FieldName()
+}
+
+func (sel navigableSelectImpl) IsTestOnly() bool {
+	return sel.Expr.AsSelect().IsTestOnly()
+}
+
+func (sel navigableSelectImpl) Operand() Expr {
+	return sel.createChild(sel.Expr.AsSelect().Operand())
+}
+
+type navigableStructImpl struct {
+	*navigableExprImpl
+}
+
+func (s navigableStructImpl) TypeName() string {
+	return s.Expr.AsStruct().TypeName()
+}
+
+func (s navigableStructImpl) Fields() []EntryExpr {
+	fieldInits := s.Expr.AsStruct().Fields()
+	fields := make([]EntryExpr, len(fieldInits))
+	for i, f := range fieldInits {
+		field := f.AsStructField()
+		fields[i] = &entryExpr{
+			id: f.ID(),
+			entryExprKindCase: navigableFieldImpl{
+				name:  field.Name(),
+				val:   s.createChild(field.Value()),
+				isOpt: field.IsOptional(),
+			},
+		}
+	}
+	return fields
+}
+
+type navigableFieldImpl struct {
+	name  string
+	val   NavigableExpr
+	isOpt bool
+}
+
+func (f navigableFieldImpl) Kind() EntryExprKind {
+	return StructFieldKind
+}
+
+func (f navigableFieldImpl) Name() string {
+	return f.name
+}
+
+func (f navigableFieldImpl) Value() Expr {
+	return f.val
+}
+
+func (f navigableFieldImpl) IsOptional() bool {
+	return f.isOpt
+}
+
+func (f navigableFieldImpl) renumberIDs(IDGenerator) {}
+
+func (f navigableFieldImpl) isEntryExpr() {}
+
+func getChildFactory(expr Expr) childFactory {
+	if expr == nil {
+		return noopFactory
+	}
+	switch expr.Kind() {
+	case LiteralKind:
+		return noopFactory
+	case IdentKind:
+		return noopFactory
+	case SelectKind:
+		return selectFactory
+	case CallKind:
+		return callArgFactory
+	case ListKind:
+		return listElemFactory
+	case MapKind:
+		return mapEntryFactory
+	case StructKind:
+		return structEntryFactory
+	case ComprehensionKind:
+		return comprehensionFactory
+	default:
+		return noopFactory
+	}
+}
+
+type childFactory func(*navigableExprImpl) []NavigableExpr
+
+func noopFactory(*navigableExprImpl) []NavigableExpr {
+	return nil
+}
+
+func selectFactory(nav *navigableExprImpl) []NavigableExpr {
+	return []NavigableExpr{nav.createChild(nav.AsSelect().Operand())}
+}
+
+func callArgFactory(nav *navigableExprImpl) []NavigableExpr {
+	call := nav.Expr.AsCall()
+	argCount := len(call.Args())
+	if call.IsMemberFunction() {
+		argCount++
+	}
+	navExprs := make([]NavigableExpr, argCount)
+	i := 0
+	if call.IsMemberFunction() {
+		navExprs[i] = nav.createChild(call.Target())
+		i++
+	}
+	for _, arg := range call.Args() {
+		navExprs[i] = nav.createChild(arg)
+		i++
+	}
+	return navExprs
+}
+
+func listElemFactory(nav *navigableExprImpl) []NavigableExpr {
+	l := nav.Expr.AsList()
+	navExprs := make([]NavigableExpr, len(l.Elements()))
+	for i, e := range l.Elements() {
+		navExprs[i] = nav.createChild(e)
+	}
+	return navExprs
+}
+
+func structEntryFactory(nav *navigableExprImpl) []NavigableExpr {
+	s := nav.Expr.AsStruct()
+	entries := make([]NavigableExpr, len(s.Fields()))
+	for i, e := range s.Fields() {
+		f := e.AsStructField()
+		entries[i] = nav.createChild(f.Value())
+	}
+	return entries
+}
+
+func mapEntryFactory(nav *navigableExprImpl) []NavigableExpr {
+	m := nav.Expr.AsMap()
+	entries := make([]NavigableExpr, len(m.Entries())*2)
+	j := 0
+	for _, e := range m.Entries() {
+		mapEntry := e.AsMapEntry()
+		entries[j] = nav.createChild(mapEntry.Key())
+		entries[j+1] = nav.createChild(mapEntry.Value())
+		j += 2
+	}
+	return entries
+}
+
+func comprehensionFactory(nav *navigableExprImpl) []NavigableExpr {
+	compre := nav.Expr.AsComprehension()
+	return []NavigableExpr{
+		nav.createChild(compre.IterRange()),
+		nav.createChild(compre.AccuInit()),
+		nav.createChild(compre.LoopCondition()),
+		nav.createChild(compre.LoopStep()),
+		nav.createChild(compre.Result()),
+	}
+}